Investigation of the Surface Functions of the Clingfish Sucker Disk Hierarchical Structures by Preparing Mimicked Structures

Abstract

Underwater adhesive materials are demand in various fields, such as biomedical applications. In nature, there are lots of aquatic livings having adhesive devices including suckers of a squid and an octopus. Herein, we had focused on a clingfish, which is widely known for using hierarchical sucker disk structures to demonstrate rapid and strong adhesion to rocky surfaces under strong currents. To investigate strong adhesion strength of a clingfish sucker disk, we had prepared mimicked structures with varying material parameters and measured its adhesion strength. The clingfish mimicked materials had successfully prepared by using anodic aluminum oxide as the mold for polystyrene or polyethylene nanofilaments and PDMS as the soft top layer. As the result of the adhesive force measurements of the prepared clingfish mimicked adhesive materials, it had revealed that the embedded nanofilament in soft materials enforces the adhesive force of the surface soft materials. Furthermore, the hardness and length of the nanofilaments, and the Young’s modulus and thickness of the mucus-mimicking PDMS layer had critical effects on the adhesion strength. According to the results, clingfish nanofilaments act as hard bracing for the soft mucus, and the structural combination of the conflicting characteristics of hardness and softness is crucial for strong adhesion.